1. Technical Field
The present invention relates to optical wavelength division multiplexing networks and, more particularly, to grooming at an orthogonal frequency division multiplexing OFDM subcarrier level with photodetection conversion of an input optical OFDM to an electrical signal.
2. Description of the Related Art
The global communication network is facing increasing demands for higher capacity, and the traffic is becoming more dynamic. As the backbone for many such networks, optical wavelength division multiplexing (WDM) networks are facing challenges to improve capacity and increase flexibility. One challenge is how to improve the spectral efficiency in the dynamic network (e.g., transmitting more data within a certain optical bandwidth) with time-varying, non-uniform traffic patterns. To tackle this challenge, network resources (such as the spectral bandwidth) need to be better utilized and shared among multiple entities that need them. By sharing these resources, the resource cost is amortized over the number of users.
A common method to solve this problem is electronic traffic grooming. A feature that is fundamental to grooming is the ability to switch low speed traffic streams into high speed bandwidth trunks, the general objective of grooming is to help decompose hard circuit provisioning problems into small, simpler ones and yield an increased solution space for such problems.
Conventionally, traffic grooming is performed by converting the input optical signals to electrical signals, using an electrical grooming fabric capable of TDM circuit switching or packet switching to perform the grooming operation, and converting the groomed electrical signals back to optical signals. Since such a grooming operation takes place between the WDM layer and the client layers and is called electronic grooming. Electronic grooming is not cost-effective or power-efficient due to the requirement of client processing at each node.